Lubricating oil thickened to a grease consistency with a mixture of a 1, 3, 5-triazine compound and a metal salt of orotic acid



United States Patent LUBRECATENG 0H. THECKENED T0 A GREASE CGNSlSTiENCY WETH A Ii HXTURE 01 A 1,3,5- TRL AZENL CQMPOUND AND A METAL SALT 0F ORSTKC ACHD John F. Hedenhurg, Cheswick, and Paul R. McCarthy, Aiiison Paris, ?a., assignors to Gulf Research & De= velopnient Company, Pittsburgh, Pa, a corporation of Deiaware No Drawing. Filed Mar. 8, 1962, Ser. No. 178,283

Claims. (Ci. ESE-33.6)

This invention relates to an improved lubricating composition and more particularly to a lubricant suitable for high temperature lubrication.

The trend in design of modern aircraft has accentuated the need for greases which Will lubricate anti-friction bearings operating at high rotational speeds and high temperatures. Considerable progress has been made in recent years in producing improved aircraft greases. For example, a number of greases are now available for lubricating bearings operating at 10,000 to 20,000 revolutions per minute at temperatures up to about 400 F. However, great difiiculty has been encountered in producing a grease which will effectively lubricate bearings operating at speeds of 10,000 to 20,000 revolutions per minute and temperatures of about 400 to about 600 F. for prolonged periods of time. Conventional aircraft greases currently available have failed to meet the stringent requirements on such a lubricant.

We have discovered that a lubricating composition having improved lubricating characteristics for an eX- tended period of time when used to lubricate bearings operating at temperatures up to about 600 F. and speeds of 10,000 to 20,000 revolutions per minute can be obtained by incorporating into a lubricating oil in oil thickening proportions a mixture of a symmetrical triazine, i.e., 1,3,5-triazine compound melt ng above about 400 F. (205 C.) having the following formula:

wherein R and R are selected from the group consisting of hydrogen, alkyl, aryl, alkaryl, aralkyl, cyanoalkyl, pyridyl, amino, hydroxy and mercapto radicals, R and R being unlike radicals when selected from the group consisting of amino, hydroxy and mercapto radicals and an alkali metal salt of orotic acid. Thus, the improved lubricating composition of our invention comprises a dispersion in a lubricating oil of a suflicient amount to thicken the lubricating oil to a grease consistency of a mixture of a 1,3,5-triazine melting above about 205 C. of the type designated by the above structural formula and an alkali metal salt of orotic acid.

The amount of the combined 1,3,5-triazine compound and alkali metal orotate which we use is an amount sn 1.- cient to thicken the lubricating oil to a grease con sistency. In general, this amount comprises about 10 to about 50 percent by weight of the total composition. The weight ratio of the 1,3,5-triazine compound to the alkali metal orotate will vary depending upon the characteristics desired in the ultimate composition. In general, however, the Weight ratio of the 1,3,5-triazine compound to the alkali metal orotate is between about 1:1 and about 10:1.

3,140,075 Patented Sept. 15, 1964 An especially preferred composition comprises a lubricating oil thickened to the consistency of a grease with a mixture of ammeline and sodium orotate in a weight ratio of about 2:1 to about 3: 1.

It will be noted that R and R in the structural formula set forth hereinabove can be the same or different radicals when selected from the group consisting of hydrogen, alkyl, aryl, alkaryl, aralkyl, cyanoalkyl and pyridyl radicals provided, of course, that the melting point of the compound is at least 205 C. When R and R are selected from the group consisting of amino, hydroxy and mercapto radicals, the radicals should not all be the same. For example, we do not intend to include compounds such as cyanuric acid (s-triazinetriol) or melamine (2,4,6- triamino-s-triazine).

It should be understood that the symmetrical (s) triazine compounds can contain other substituents provided, of course, that said other substituents do not adversely affect the beneficial oil thickening properties of the striazine compounds.

An especially preferred group of triazine compounds for the purpose of the invention includes those compounds wherein each of the R radicals is an amino radical, that is, a vguanamine derivative. Preferred guanamine derivatives are those wherein R is selected from the -group consisting of hydrogen, alkyl (e.g., methyl, ethyl, propyl and n-butyl), aryl (e.g., phenyl and naphthyl), alkaryl (e.g., tolyl), aralkyl (e.g., benzyl), cyanoalkyl (e.g., cyanoethyl, cyanobutyl and cyanooctyl), pyridyl, hydroxy and rnercapto radicals. When R in the guanamine derivatives is an alkyl radical, it preferably is selected from the group consisting of methyl, ethyl, propyl and n-butyl radicals in order to give a compound having a melting point above about 205 C. When R is isobutyl or a higher alkyl radical the melting point of the resulting substituted guanamine is below 205 C. While compounds melting below 205 C. can be used to produce grease compositions for use at temperatures below 400 R, such compounds are not satisfactory thickening agents for grease compositions used to lubricate bearings operating at high rotational speeds at temperatures of 400 to 600 F. and higher for prolonged periods of time. When R in the guanamine derivatives is an alkaryl or an aralkyl radical, the alkyl portion of the alkaryl and aralkyl radicals preferably contains not more than 2 carbon atoms. When R in the preferred guanamine derivatives is a cyanoalkyl radical, thealkyl portion of the cyanoalkyl radical can contain as many as 8 carbon atoms and still give a compound melting above 205 C.

Illustrative of the preferred guanamine derivatives which can be used in the present invention are the following:

2,4-diamino-l,3,5-triazine 2,4-diamino-6-methyl- 1, 3,5 -triazine 2,4-diamino-6-ethyl-l,3,5-triazine 2,4-diamino-6-propyl-l ,3 ,5 -triazine 2,4-diamino-6-n-butyl-1,3,S-triazine 2,4-diarnino6-phenyl-l ,3 ,5 -triazine 2,4-diamino-6-u-naphthyl-1,3,5-triazine 2,4-diamino-6-B-naphthyl-1,3,5-triazine 2,4-diamino-6-m-tolyl-1,3,5-triazine 2,4-diamino-6-p-tolyl-1,3,5-triazine 2,4-diamino-6-benzyl-1,3,5-triazine 2,4-diamino--cyanoethyl- 1,3,5 -triazine 2,4-diarnino-6-cyanobutyl-1,3,5-triazine 2,4-diamino-6-cyanooctyl-1,3,5-triazine 2,4-diamino-6-pyridyl-1,3,5-triazine 2,4-diamino-6-hydroxy- 1 ,3,5-triazine 2,4-diamino-6-mercapto-1,3,5-triazine armo While the guanamine derivatives of the above type are all efi'ective thickeners for the preparation of high temperature greases, it is not to be implied that all serve with equal efficiency, since the various compounds may vary to some extent depending upon the nature and severity of the service to which they are subjected. That guanamine derivative which contains a hydroxy radical, i.e., 2,4-diamino-6-hydroxy-1,3,5-triazine (ammeline) is an especially preferred compound for use in the grease composition of the present invention.

The 1,3,5-triazine compounds can be prepared according to known chemical procedures. Neither the compounds per se nor their preparation constitutes any portion of theinvention. For example, a 2-amino-4,6-dialkyl-1,3,5-triazine can be prepared by reacting a nitrile with guanidine. A 2,6-diamino-4-alkyl-l,3,5-triazine can be prepared by reacting alkyl biguanides with acylating agents in the presence of alkali. Acetoguanamine (2,4- diamino-fi-methyl-l,3,5-triazine) having a melting point of 271 to 273 C. can be prepared by reacting dicyan- A diamide and acetonitrile in the presence of piperidinev Benzoguanamine (2,4-diamino 6 phenyl-l,3,5-triazine) having a melting point of 222 C. can be prepared by reacting dicyandiamide and benzonitrile in the presence of piperidine. 2,4-diamino-6-(2'-naphthyl)-l,3,5-triazine having a melting point of 240 C. can be prepared by reacting beta-naphthonitrile and dicyandiamide in the presence of piperidine. 2,4-diamino-6-benzyl-l,3,5-triazine having a melting point of 232 C. can be prepare by reacting dicyandiamide and benzylcyanide in the presence of piperidine. The preparation of some of the 1,3,5-triazines is more fully described in US. Patent No. 2,527,314, issued October 24, 1950, to Johnstone S. Mackay; US. Patent No. 2,302,162, issued November 17, 1942, to Werner Zerweck et al.; and US. Patent No. 2,408,694, issued October 1, 1946, to John Kenson et al.

The amount of 1,3,5-triazine compound used may vary over wide limits depending upon the particular oil with which the triazine compound is to be blended and upon the properties desired in the final lubricating composition. While as much as 45 percent by weight of the total composition may comprise the triazine compound, We prefer to use smaller amounts, that is, in the order of about 10 to about percent by weight. It should be understood, however, that, depending upon the consistency of the composition desired and upon the amount of the alkali metal orotate used in combination therewith, less than 10 percent or more than percent of the triazine compound may be employed. The 1,3,5-triazine compound generally comprises about 5 to about 45 percent by weight of the total composition.

The alkali metal salt of orotic acid can be prepared simply by treating orotic acid with an aqueous alkali solution. Neither the compounds per se nor their method of preparation constitutes any portion of the invention. For example, sodium orotate can be prepared by reacting aqueous sodium hydroxide and orotic acid in equimolar proportions at 80 C. The amount of the alkali metal salt of orotic acid which we use in the composition of the invention may vary over wide limits depending upon the particular lubricating oil with which the alkali metal orotate is blended, the particular 1,3,5- triazine compound employed and upon the characteristics desired in the ultimate composition. In general, the amount of the alkali metal orotate is about 5 to about 20 percent by weight of the total composition.

The lubricating oil in which the triazine compound and the alkali metal salt of orotic acid are incorporated is preferably a lubricant of the type best suited for the particular use for which the ultimate composition is designed. Since many of the properties possessed by the lubricating oil are imparted to the ultimate lubricating composition, we advantageously employ an oil which is thermally stable at the contemplated lubricating temperature. Some mineral oils, especially hydrotreated mineral oils, are sufliciently stable to provide a lubricating base for preparing lubricants to be used under moderately elevated temperatures. In general, however, where temperatures in the order of 400 to 600 F. are encountered, synthetic oils form a preferred class of lubricating bases because of their high thermal stability. The synthetic oil can be an organic ester which has a majority of the properties of a hydrocarbon oil of lubricating grade such as di-Z-ethylhexyl sebacate, dioctyl phthalate and dioctyl azelate. Instead of an organic ester, we can use polymerized olefins, copolymers of alkylene glycols and alkylene oxides, polyorgano siloxanes, polyaryl ethers and the like.

The liquid polyorgano siloxanes and certain polyaryl ethers because of their exceedingly high thermal stability form a preferred group of synthetic oils to which the triazine compound and the alkali metal salt of orotic acid are added. The polyorgano siloxanes are known commercially as silicones and are made up of silicon and oxygen atoms wherein the silicon atoms may be substi tuted with alkyl, aryl, alkaryl, aralkyl and cycloalkyl radicals. Exemplary of such compounds are the dimeth yl silicone polymers, diethyl silicone polymers, ethylphenyl silicone polymers and methyl-phenyl silicone polymers. Exemplary of an exceedingly good polyaryl ether is a polyphenyl ether, i.e., m-bis(m-phenoxyphenoxy) benzene.

If desired, a blend of oils of suitable viscosity may be employed as the lubricating oil base instead of a single oil by means of which any desired viscosity may be secured. Therefore, depending upon the particular use for which the ultimate composition is designed, the lubricating oil base may be a mineral oil, a synthetic oil, or a mixture of mineral and/or synthetic oils. The lubricating oil content of the compositions prepared according to this invention comprises about 50 to about percent by weight of the total composition.

In compounding the compositions of the present invention, various mixing and blending procedures may be used. In a preferred embodiment of the invention, the lubricating oil, the triazine compound and the alkali metal salt of orotic acid together with conventional lubricant additives, if desired, are mixed together at room temperature for a period of about 10 to 30 minutes to form a slurry. During this initial mixing period some thickening is evidenced. Some lumps may be formed. The slurry thus formed is then subjected to a conventional milling operation in a ball mill, a colloid mill, homogenizer or similar device used in compounding greases to give the desired degree of dispersion. In the illustrative compositions of this invention, the slurry was passed twice, by means of a pump, through a Premier Colloid Mill set at a stator-rotor clearance of 0.002 inch. Maximum thickening occurred on the second pass through the mill.

The lubricating composition of this invention can contain conventional lubricant additives, if desired, to improve other specific properties of the lubricant without departing from the scope of the invention. Thus, the lubricating composition can contain a filler, a corrosion and rust inhibitor, an extreme pressure agent, an anti-oxidant, a metal deactivator, a dye and the like. Whether or not such additives are employed and the amounts thereof depend to a large extent upon the severity of the conditions to which the composition is subjected and upon the stability of the lubricating oil base in the first instance. Since the polyorgano siloxanes, for example, are in general more stable than mineral oils, they require the addition of very little, if any, oxidation inhibitor. When such conventional additives are used they are generally added in amounts between about 0.01 and 5 percent by weight based on the weight of the total composition.

In order to illustrate the improved lubricating characteristics of a grease composition of the invention when used to lubricate a bearing operating at 600 F. and ro- 5 6 tational speeds of 10,000 and 20,000 revolutions per min Table l ute a slight modification of the test procedure outlined C b h A by the Coordinating Research Council Tentative Draft l fl f y (July 1954), Research Technique for the Determination il QF 6-7 39 of Performance Characterisltics g l rbricating G i 5 S 3 x ag 1O Antifriction Bearings at Eevate emperatures, Designation L-35 was used. In the present evaluations, lnspecnon-penetrauon (ASTM 13217421): about 6 to 7 grams of the grease to be tested are placed i $21 25: a bearing assembly containing an eight-ball SAE N 204 f; ball hearing. The bearing assembly which is mounted on 10 Dmppmg (ASTM 13566-42) "3 830+ a horizontal spindle is subjected to a radial load of 5 Performance IOOOO 127 pounds. The portion of the spindle upon which the test The long performance lif f the composition f the bearing assembly is located is encased in a thermostaticalinvention at a high rotational speed and a high tempera, 3 controlled Oveh- Y this means the temperature of the ture is self evident from the above data. When this combearing can be maintained at a desired elevated temperaposition was Subjected to a test using p spindles and ture which in the tests reported hereinafter was 600 F. an MRC 204 17 bearing at 600 R and 20 000 l The Spindle is driven by a Ph helt'tehsioh motor tions per minute, a performance life of 164 hours was drive assembly, Capable of glvlhg Splhdle Speeds P to obtained. When the same composition was tested using 20,000 revolutions per minute. The spindle is operated p spindles and an MRC 204 17 bearing at 400 On a Cycling Schedule Consisting of a Series of P 20 and 20,000 revolutions per minute, a performance life in each period consisting of 20 hours running time and 4 excess f 510 hours was b i d hours shutdown time. The test continues until the lubri- Other lubricating compositions within the scope of the cant fails. The lubricant is considered to have failed invention are illustrated inTable II.

Table II Composition, Percent By Weight B C D E F G H I .T K L M N O P Lubricating Oil:

DC 550 Fluid 90 80 70 G.E. Silicone 81717 Di-Z-cthylhexyl sebacate 1,3,5-Triazine Compound:

Benzoguanamine (2,4-d1ammo-6phenyl-L3,

5-triazine) Anlmelide (2,4-dihydroxy6-aminol,3,5-

triaziue) diamino-G-hydroxy-1,3,5- triazine) 2,4Dihydroxy-G-pyridyl-L3,fi-triazme 2,4-Dirnercapto-Eamino-l,3,5-triazine 2,4-Diamino-1,3,5-triazine 2,4-Diamino-6-methyl-L3,5-trta inp ZA-DiaminoG-ethyl-l,3,5-triaeine 2,4-Diamino6-n-buty1-l,3,5-triazine 2,4-Diamino-6-benzyl-l,3,5 triazine 2,4Diamino-6-cyano0ctyl-1,3,5-triminp Alkali Metal Salt of Orotic Acid:

Sodium orotate Potassium orotate Lithium orotate Ratio of triazine compound to alkali metal orotnte when any one of the following conditions occurs, (1) spindle input power increases to a value approximately 300 percent above the steady state condition at the test temperature; (2) an increase in temperature at the test bearing of 20 F. over the test temperature during any portion of a cycle; or (3) the test bearing locks or the drive belt slips at the start or during the test cycle.

The lubricating oil used in preparing the lubricating composition shown in Table I was a synthetic oil known as QF-6-7039 Fluid marketed by Dow-Corning Corporation. This fluid is considered to be a methylphenylsiloxane polymer wherein the en silicon atoms are substituted to a high degree by two phenyl groups and one methyl group. The material is highly resistant to radiation and contains an antioxidant.

In preparing the lubricating composition, the oil, the triazine and the sodium orotate were mixed at room temperature for a period of l0 to minutes. The slurry thus formed was passed twice through a Premier Colloid Mill set at a stator-rotor clearance of 0.002 inch. The thickened lubricating composition thus prepared had the following approximate make-up and properties.

GE. Silicone 81717 is marketed by general Electric Company and is a water-white to amber liquid polymer of the general formula [Ai (CH 08i (CH OSi (CH O] x It has a viscosity at 65 F. of 3487 centistokes, at 0 F. of 390 oentistokes, at F. of 71.3 centistokes, at 210 F. of 22 centistokes and at 700 F. of 1.9 centistokes. DC 550 fluid is marketed by Dow-Corning Corporation and is a methylphenylsiloxane polymer having as typical characteristics a viscosity at 100 F. of 300 to 400 SUS, a viscosity-temperature coefficient of 0.75, a freezing point of 54 F., a flash point of 600 F. and a specific gravity 25 C./25 C. of 1.08.

While our invention has been described with reference to various specific examples and embodiments, it will be understood that the invention is not limited to such examples and embodiments and may be variously practiced within the scope of the claims hereinafter made.

We claim:

1. A lubricating composition comprising a dispersion in a lubricating oil selected from the group consisting of araaore polyorgano siloxanes, organic esters and polyaryl ethers of a sufiicient amount to thicken the lubricating oil to a grease consistency of a mixture of a 1,3,5-triazine compound melting above about 205 C. having the following formula:

wherein R and R are selected from the group consisting of hydrogen, alkyl, aryl, alkaryl, aralkyl, cyanoalkyl, pyridyl, amino, hydroxy and mercapto radicals, R and R being unlike radicals when selected from the group consisting of amino, hydroxy and mercapto radicals and an alkali metal salt of orotic acid.

2. The lubricating composition of claim 1 wherein the combined 1,3,5-triazine compound and alkali metal salt of orotic acid comprises about 10 to about 50 percent by weight of the total composition and the weight ratio of the 1,3,5-triazine to the alkali metal salt of orotic acid in said mixture is about 1:1 to about 10:1.

3. The lubricating composition of claim 1 wherein the lubricating oil is a polyorgano siloxane.

4. The lubricating composition of claim 1 wherein the alkali metal salt of orotic acid is sodium orotate.

5. The lubricating composition of claim 1 wherein the alkali metal salt of orotic acid is potassium orotate.

6. The lubricating composition of claim 1 wherein the alkali metal salt of orotic acid is lithium orotate.

7. A lubricating composition comprising a dispersion in a lubricating oil selected from the group consisting of polyorgano siloxanes, organic esters and polyaryl ethers of a sufiicient amount to thicken the lubricating oil to a grease consistency of a mixture of a guanamine derivative melting above about 205 C. having the following formula:

1' wherein R is selected from the group consisting of hydrogen, alkyl, aryl, alkaryl, aralkyl, cyanoalkyl, pyridyl, hydroxy and mercapto radicals and an alkali metal salt of or-otic acid.

8. A lubricating composition comprising a dispersion in a liquid polyorgano siloxane of a suflicient amount to thicken the polyorgano siloxane to a grease consistency of a mixture of ammeline and sodium orotate wherein the weight ratio of ammeline to the sodium orotate in said mixture is about 1:1 to about 10:1.

9. A lubricating composition comprising a dispersion in a liquid polyorgano siloxane of a suflicient amount to thicken the polyorgano siloxane to a grease consistency of a mixture of ammeline and potassium orotate wherein the weight ratio of ammeline to the potassium orotate in said mixture is about 1:1 to about 10: 1.

10. A lubricating composition comprising a dispersion in a liquid polyorgano siloxane of a sufficient amount to thicken the polyorgano siloxane to a grease consistency of a mixture of ammeline and lithium orotate wherein the weight ratio of ammeline to the lithium orotate in said mixture is about 1:1 to about 10:1.

Larsen et a1 Mar. 27, 1945 Halter et a1 May 16, 1961 

1. A LUBRICATING COMPOSITION COMPRISING A DISPERSION IN A LUBRICATING OIL SELECTED FROM THE GROUP CONSISTING OF POLYORGANO SILOXANES, ORGANIC ESTERS AND POLYARYL ETHERS OF A SUFFICIENT AMOUNT TO THICKEN THE LUBRICATING OIL TO A GREASE CONSISTENCY OF A MIXTURE OF A 1,3,5-TRIAZINE COMPOUND MELTING ABOVE ABOUT 205*C. HAVING TGHE FOLLOWING FORMULA: 